As is widely known, a considerable difficulty is involved in conducting by manual works, such kind of works as the cleaning and the conditioning of the substrate surface prior to painting of the inner and outer wall surfaces, in a ship, high-rise building, huge tank, or the like. For this reason, automating those works without relying on manual works has been studied, and various apparatus for the automation have been proposed.
For example, Japanese Examined Patent Publication No. Sho 60-28715 discloses an apparatus which adheres onto a wall surface and moves along the wall surface, wherein the apparatus basically comprising a pressure-receiving body, wheels for driving an apparatus body, seal for defining a depressurized space in cooperation with the pressure-receiving body and with the outer wall surface, and a depressurization source for discharging fluid from the depressurized space. Also, Japanese Examined Patent Publication No. Sho 60-26752 discloses an apparatus comprising, in addition to that basic arrangement, a mechanism for blast cleaning by projecting blast material onto a wall surface which the apparatus suction-adheres onto and moves along.
In these conventional apparatus, for the purpose of moving the apparatus along a wall surface, a space defined by a casing as the pressure-receiving body and the wall surface is depressurized, while to the casing is attached a seal member which is made of a substantially unbreathable and pliable material, and through the seal member the casing closely adheres to the wall surface. The apparatus adheres by suction onto the wall surface by reducing the pressure within the substantially sealed space between the apparatus and the wall surface lower than the pressure outside the apparatus. While maintaining the suction-adhered condition, the apparatus moves along the wall surface with driving wheels coupled to the apparatus. The apparatus is capable of conducting blast cleaning, for example, by projecting blast material onto the wall surface along which the apparatus moves.
By the way, in conducting such works as the cleaning and the conditioning of the substrate surface prior to painting of the inner and outer wall surfaces, in a ship, high-rise building, huge tank, or the like, it is known that a difficulty is involved in the works in a corner where two wall surfaces intersect at a specified angle. The conventional apparatus, however, have not been capable of dealing with a corner where two wall surfaces intersect each other at a specified angle, though the apparatus are capable of dealing with one wall surface (which is typically a flat one).
It is a primary object of the present invention to provide a self-drive blast apparatus which is capable of moving along two wall surfaces which intersect at a specified angle while keeping suction-adhered onto the wall surfaces, and capable of conducting and blast cleaning by injecting blast material onto an portion wherein the two wall surfaces intersect and the vicinity thereof.